Hi all,
I've been looking for where Pope Pius XI explicitly explains that he is putting the feast at the end of October so that it can be emphasised that His Social Reign is to come in this world before the end of the world, reflected by the end of the liturgical calendar, and is not only a spiritual kingdom.
The encyclical Quas Primas itself merely states:
"The last Sunday of October seemed the most convenient of all for this purpose, because it is at the end of the liturgical year, and thus the feast of the Kingship of Christ sets the crowning glory upon the mysteries of the life of Christ already commemorated during the year, and, before celebrating the triumph of all the Saints, we proclaim and extol the glory of him who triumphs in all the Saints and in all the Elect."